A steelmaker based in Poland is saving nearly €3 million per year after switching to NSK’s sealed-clean KVS bearings in its roll mill. Such has been the superior performance of these four-row tapered roller bearings that the company has adopted this solution for all of its tandem cold mills.
The steel mill in Poland started production in the 1970s. After many years of operation, the management team decided that a refurbishment was necessary. To help reduce costs, the mill consulted with a local technical university on the potential for changing the roll mill bearings from oil mist to oil bath lubrication. Oil mist lubrication was seen as problematic, but switching to oil bath lubricated bearings did not result in the expected improvements and the mill was left with a significant issue.
Determined to resolve the issue, the team at the steelmaker turned to the expertise of NSK and its Added Value Programme AIP. Specialist NSK engineers reviewed the mill design and proposed the adoption of sealed-clean KVS bearings with grease lubrication. Heeding the advice, the four-row, tapered roller bearings were duly installed and, after one year of operation, were still providing excellent performance and productivity. As a result, the customer adopted these bearings for all of its tandem cold mills, where they are now delivering superior operating life and reduced maintenance costs compared with the previous solution.
NSK KVS bearings offer 2-4 times longer life than standard bearings. There are many reasons behind this elevated level of performance. For instance, a special type of bore seal averts the build-up of negative pressure that can cause the entry of water through the main seals. Other design attributes include a special helical groove that prevents creeping on the roll neck shaft, while innovative internal bearing geometry and a special seal help provide higher load capacity.
Pre-lubricated with the recently developed AQGRD water-resistant grease, KVS bearings are available in different material specifications, and in open or sealed design.
At the Polish steel mill, thanks to the reduction in the number of bearings required, less downtime, fewer service hour requirements and the elimination of lubricating oil (NSK KRV bearings are pre-installed with grease), the mill is saving €2,997,568 per annum.